1. Field of the Invention
The present invention relates to a cleaning liquid and a cleaning method for removing etching residues formed on the surfaces of semiconductor devices and display devices in the production thereof, and particularly to a cleaning liquid and a cleaning method for removing etching residues, which firmly adhere to the surfaces of semiconductor devices and display devices, without damaging the materials of semiconductor devices and display devices such as metal wirings, interlayer insulation films, etc.
2. Description of the Prior Art
At present, semiconductor devices such as highly integrated LSI are generally produced by lithographic methods. The lithographic production of semiconductor devices generally includes sequential step: a step of forming electroconductive thin films, such as metal films, which are finally made into wirings; a step of forming interlayer insulation films such as silicon oxide films for insulating electroconductive thin films and wirings on a substrate such as silicon wafer; a step of forming an overlying photosensitive layer by coating a photoresist uniformly; a step of forming a patterned resist film by a pattern exposure and subsequent development of the photosensitive layer; a step of patterning the underlying thin films by a selective etching utilizing the patterned resist film as a mask; and a step of removing the remaining patterned resist film completely.
Recently, semiconductor devices come to be integrated more highly, and the formation of a pattern of 0.18 μm or smaller is required. As the processing dimension becomes extremely finer, the dry etching has come to dominate in the selective etching process. In the dry etching process, it is known that residues derived from dry etching gas, resist, film to be etched and materials of the treating chamber of dry etching apparatus (hereinafter, the residues will be referred to as “etching residues”) are formed. The etching residues remaining inside and around via holes unfavorably increase the resistance and cause electric short circuits.
As the cleaning liquid for removing etching residues formed during the formation of metal wirings, organic amine-containing stripping liquids composed of a mixture of an alkanolamine and an organic solvent have been disclosed (JP 62-49355A and JP 64-42653A). When the proposed stripping liquids are washed with water after removing etching residues and remaining resist, the amine is dissociated by the absorbed water and the stripping liquids become alkaline, to corrode metal films, etc. Therefore, an organic solvent such as an alcohol, in place of water, must be used as the rinsing liquid, to reduce the safety and increase environmental load.
As the cleaning liquid more powerful in removing etching residues and resist films than the organic amine-containing stripping liquids, fluorine-containing cleaning liquids composed of a fluorine compound, an organic solvent, a corrosion inhibitor, etc. have been disclosed (JP 7-201794A and JP 11-67632A). Under recent severe conditions of dry etching in the production of semiconductor devices, the resists are degraded significantly. The proposed organic amine-containing stripping liquids and fluorine-containing cleaning liquids are less effective for completely removing such degraded resists.
Since the organic amine-containing stripping liquids and the fluorine-containing cleaning liquids contain a large amount of organic solvents, the use thereof in the production of semiconductor devices necessitates undue precautions for safety and for reducing environmental load, such as the treatment of liquid wastes. To remove such drawbacks, acid-containing cleaning liquids such as an aqueous solution of an organic acid and an aqueous solution of nitric acid, sulfuric acid and phosphoric acid have been proposed (JP 10-72594A and JP 2000-338686A). However, the proposed acid-containing cleaning liquids are less effective for removing firmly adhered etching residues, particularly, etching residues containing silicon, silicon oxides, copper oxides, etc.
Therefore, there has been a strong demand for a cleaning liquid that removes etching residues, particularly, etching residues containing silicon, silicon oxides, copper oxides, etc. completely without damaging the wiring materials, particularly, copper and that is highly safe and environmentally friend.